This invention relates to attachments for skid-steer loaders. Skid-steer loaders are generally known as compact loaders having two fixed axles on which four drive wheels are mounted. For driving forward and rearward, wheels on opposite sides are driven in a uniform sense of rotation. The loaders turn in a tight circle by uniformly driving wheels on opposite sides of the loader in opposite senses of direction. The opposite rotation of the wheels causes the loader to turn while the wheels skid laterally, hence "skid-steer".
Examples of skid-steer loaders are made by three companies, Melroe, Toyota and New Holland. Melroe Company of Fargo, N. Dak., which is business unit of Clark Equipment Company, makes and sells skid-steer loaders under the trademark "Bobcat". Traditionally, the loaders are provided with scoops which are loaded in the lower position by driving the skid-steer into dirt or a pile of material and then raising the scoop on arms. Usually the arms are angular arms which are hinged to supports in upper positions near the rear of the loaders. The arms are raised by hydraulic rams hinged between positions lower on the support and lower on the arms. Other hydraulic rams tilt an attachment plate on which the scoop or bucket is mounted.
Current examples of "typical" skid-steer loaders are:
(1) The Bobcat 643 Series Loader, with SAE-rated operating capacity of 1,000 lbs., load a 86.3 inches (7.2 ft.) and tipping load of 2,200 lbs.
(2) The Toyota 2SDK7 Loader, SAE-rated at 1,150 lbs. operating load and 2,300 lbs. tipping load at 86.2 inches height (7.2 ft.).
The Society of Automotive Engineers (SAE) rates this type of equipment operating capacity with a standard digging bucket according to SAE Standard No. J818B--"Operating capacity to equal no more than one-half the tipping load".
Skid-steer loaders, called Bobcats by the leading U.S. manufacturer of skid-steer loaders, have been available in the United States for nearly three decades. The original market for the skid-steer loaders existed in agriculture, where there was a need for an economical and highly mobile rubber-tired loader. Their uses included transporting and mixing feedstock, cleaning animal stalls, and general handling of bulk materials.
In 1974, the market for skid-steer loaders reached peak sales of approximately 21,000 units. As the American agricultural economy suffered in that year, likewise the market for skid-steers plummeted.
More recently skid-steer loaders have found uses in the construction industry.
As a current example, one large dealer of Toyota skid-steer loaders reported sales and leases of 170 units in 1986. Of that number, only ten percent of the sales were for agricultural use, and 75 percent were sold for use in construction. Total dollar volume in skid-steer loaders by that one dealer in 1986 was approximately 2.7 million dollars.
Many attachments are made to be secured to the attachment plates. As an example, Melroe advertises angle brooms, back hoes, box scrapers, earth augers, pallet forks, utility forks, scarifiers, york rakes, trenchers, farm grapples, blades which may be reset at desired angles and landscape rakes for Bobcat loaders. Melroe also advertises vertical masts which may be attached to the loaders independently of the lifting arms.
From Toyota and Bobcat, two leading manufacturers of skid-steers, there is currently no attachment for crane-conversion. Those manufacturers were skeptical that such devices would work.
In other fields, there are crane attachments that can be purchased that: 1) bolt to the bed of a truck, or B) devices that slide over the forks of a forklift. However, those latter devices are not related to skid-steer loaders.
None of the attachments currently available from Melroe Bobcat, Toyota or New Holland provide for lifting items high in the air to place or remove items between ceiling beams or the like.
A need exists for a mini-crane attachment which is suitable for use with skid-steer loaders.